1. Field of the Invention
This invention generally relates to a prodrug formed of heparin and a drug and drug-delivery stents formed from a material having the prodrug.
2. Description of the Background
Blood has a property of being coagulated by the action of various components in blood when it has come into contact with foreign matter. Hence, there is a need for a high anticoagulant property in component materials for medical articles or instruments used on the part coming into contact with blood, as exemplified by artificial hearts, artificial cardiac valves, artificial blood vessels, blood vessel catheters, cannulas, pump-oxygenators, blood vessel by-pass tubes, intraaortic balloon pumps, transfusion instruments and extracorporeal circulation circuits.
Heparin has been commonly used to impart anticoagulant properties to the medical devices, but a systemic use of heparin may undesirably lead to the formation of a large number of bleeding nests. Methods have been developed to minimize side effects associated with the use of heparin with limited success (see, for example, U.S. Pat. Nos. 5,270,064 and 6,630,580). Meanwhile, problems associated with systemic administration of a drug have led to the development of methods for local delivery of the drug. Administration of a pharmacologically active drug directly to a patient may lead to some undesirable consequences because many therapeutic drugs have undesirable properties that may become pharmacological, pharmaceutical, or pharmacokinetic barriers in clinical drug applications.
Therefore, in the art of drug-delivery implantable medical devices, there is a need for minimizing the side effects associated with the use of heparin and a drug.
The present invention addresses such problems by providing a coating composition and a coating formed thereof including a prodrug formed of heparin and a drug.